Smart grid technology refers to ongoing improvements for the transmission and distribution of electricity from points of generation to consumers. A key component in a smart grid network is the so-called “smart-metering” network. In a typical smart-metering network, electricity (or other utility) meters located at a residency or other edifice are able to transmit the real-time meter readings through powerlines back to the power concentrators and provide valuable real-time electricity control and billing information for the electricity provider.
Due to power efficiency considerations and severe noise in powerlines, direct transmission of metering information through power lines has limited scopes. Therefore, a typical smart metering network has a tree-like topology, including: 1) a data concentrator that serves as the root node in the tree (also called a base node, BN); 2) metering devices at terminal nodes (TNs) in the tree which send their metering readings back to the BN; and 3) switching nodes (SWs) which act as the branch nodes in the tree. The SWs relay the data traffic to the further hops for communication pairs (e.g., a TN and a BN) beyond the direct communication reach. The SWs and TNs in the network are collectively referred to herein as service nodes (SNs).
Powerline-Related Intelligent Metering Evolution (PRIME) is a European standard of smart-metering network. The PRIME standard defines lower layers of a powerline communication narrowband data transmission system for the electric power grid using Orthogonal Frequency-Division Multiplexing (OFDM) in the 42-90 kHz band. A PRIME network utilizes a tree-like topology as described above. In a PRIME network, the Media Access Control (MAC) function enables the BN, as well as the SWs to send out beacons periodically. The beacons also help all the SNs in the network synchronize their clocks and virtually chop the time domain into discrete time frames.
A Keep Alive (KA) procedure is used to detect whether the BN and SNs are alive. KA frames allow the BN to detect when a SN becomes unreachable due to changes in network configuration/topology (bad link, channel conditions, load variations, SN leaving the subnetwork, etc.), or fatal errors at the SN it cannot recover from.
Conventional KA procedures require the BN to send KA request frames (referred to as ALV_B) to each of the SNs in the network and look for KA response frames from the SNs (referred to as ALV_S). However, when the network size increases by adding several SNs, the KA traffic causes network stability issues as depicted in the communications network 100 shown in FIG. 1 which shows a BN 110 communicating with 3 terminal Nodes (TNs) shown as TN1, TN2, and TN3 through a SW shown as SW1. The high traffic depicted can happen especially when the network traffic is already high, such as due to a firmware upgrade.
During high traffic conditions it may become difficult to guarantee end-to-end delivery of KA messages because the network congestion increases due to added data traffic. For example, in networks such as in a PRIME compliant network, Loss of KA messages can lead to unintended node deregistration from the network.